Genetic map of S. oneidensis MR-1 showing the location of the genes encoding Maf-1 (so3273) and Maf-2 (so3259) depicted in blue. Genes maf-1 and maf-2 are within the large genetic motility island, flanking the putative pseudaminic acid (Pse) biosynthesis gene cluster of S. oneidensis MR-1 (also called as Shewanella flagellin modification or sfm operon 4). Putative Pse biosynthesis genes are depicted in gray, while the gene encoding GlfM is colored in yellow. Structures of Maf-1 and Maf-2 are predicted using AlphaFold v212,13 and visualized using ChimeraX.14,15 The N-terminal region of both proteins is colored in magenta, while the signature MAF-flag10 domain or domain of unknown function (DUF) 115 is shown in turquoise, and the predicted tetratricopeptide repeat (TPR) domain of Maf-1 is colored in yellow. Essential (putative) catalytic residues of both Maf-1 (D247) and Maf-2 (D261) are also indicated. The figure also depicts the glycosylation of flagellin by either Maf-1 or Maf-2-GlfM complex before export (thick arrow) via the flagellar secretion apparatus, through the hook-basal body (HBB), and along the filament channel, followed by its polymerization at the distal tip of the flagellar filament by a capping protein. IM, inner membrane; PG, peptidoglycan; OM, outer membrane; CMP, cytidine monophosphate.
